The invention relates to an impeller for a feed pump designed, in particular, as a side channel pump or as a peripheral pump. This impeller has, in each of its end faces, a ring of guide vanes delimiting vane chambers and possesses a driver for fastening said impeller fixedly in terms of rotation to a correspondingly designed drive.
Such impellers have, usually at their center, a nonround recess as a driver and can be slipped onto a shaft of an electric motor, the impellers being mounted with axial play on said shaft. As a rule, the impellers are manufactured from plastic by the injection molding method or are sintered. The feed pump provided with such an impeller is often used as a fuel pump in present-day motor vehicles. In order to achieve as high an efficiency as possible and low noise emissions with the feed pump, the guide vanes usually have a very high angle of inclination to the perpendicular on the end faces of the impeller. Moreover, in the case of impellers with axial throughflow, vane chambers located opposite one another are connected to one another. One disadvantage of the known impeller is that it is very complicated to remove it from the mold. In this case, an injection mold, a stamping mold or a compression mold has to be drawn apart during a rotational movement. Furthermore, the impeller requires a core for the driver, since the latter is usually oriented perpendicularly to the end faces of the impeller. The result of this is that the manufacture of the impeller is highly cost-intensive.
There has already been the idea of composing the impeller of two disk parts and, for example, of arranging a ring of guide vanes in each of the disk parts. The disk parts each have a driver, by means of which they are slipped onto the shaft of the electric motor. As a result, in the mounted state, the disk parts are pressed against one another by the pressure within the vane chambers. A disadvantage of this, however, is that the driver has tolerances, so that the disk parts can be aligned relative to one another only with a great degree of inaccuracy. Furthermore, the internal pressure in the vane chambers is often not sufficient to press the disk parts reliably against one another. The result of this is that the feed pump has very low efficiency.
The problem on which the invention is based is to design an impeller of the type initially mentioned, in such a way that it can be produced very cost-effectively and a feed pump provided with it has particularly high efficiency.
This problem is solved, according to the invention, in that the impeller is composed of at least two disk parts lying one above the other and in that the disk parts are connected fixedly in terms of rotation to one another.
By virtue of this design, the guide vanes can be configured with very high angles of inclination and with inclination directions opposite to one another on the two end faces and can be manufactured in a very simple way. This design of the angle of inclination leads to particularly low noise emissions. Since the disk parts are connected outside the center of the impeller, forces acting on the disk parts are reliably supported. The feed pump provided with the impeller according to the invention has very high efficiency because of the rotationally fixed design of the connection of the disk parts. The invention makes it possible to manufacture virtually any desired design of guide vanes and of connections between vane chambers located opposite one another.
In an advantageous refinement, the two disk parts are pressed onto a driver located at their center. The driver has an outer contour differing from the circular shape, preferably a square contour. Other contours, for example a toothed profile, are, however, also possible. Furthermore, the driver possesses a receptacle for the drive shaft of the electric motor. In the simplest instance, this receptacle is a bore which has a flattening at one point on its circumference. Since the driver is usually arranged in the center of the impeller, it is therefore not necessary for all the disk parts to be provided with a driver. In the simplest instance, each of the disk parts can be manufactured in a coreless two-part mold. The manufacture of the impeller thereby becomes highly cost-effective.
According to a further refinement of the invention, the disk parts can be connected to one another in a simpler way if they are connected fixedly in terms of rotation to one another outside the center of the impeller.
It is advantageous, at the same time, if one of the disk parts has a projecting collar and the disk part located opposite the collar has a recess for receiving said collar.
According to another advantageous development of the invention, when the disk parts are pressed together the vane chambers are aligned particularly reliably relative to one another if the disk parts have rotation prevention means engaging positively one into the other.
According to another advantageous development of the invention, the disk parts, when being pressed together, are aligned relative to one another, without additional rotation prevention means, if at least one of the disk parts has bores for pressing together with a stud connected fixedly in terms of rotation to the other disk part.
The impeller according to the invention consists of particularly few components if the studs are formed in one piece with one of the disk parts.
According to another advantageous development of the invention, the disk parts can be designed identically if the studs are arranged in bores. This design results in a pronounced reduction in the costs of the dies necessary for producing the impeller according to tire invention. For example, two or more straight pins or dowel pins are suitable for reliable pressing together.
The impeller according to the invention has an intended height, irrespective of the pressures prevailing in the impeller, if the disk parts are adhesively bonded or welded to one another. This design likewise results in particularly high efficiency of the feed pump provided with the impeller according to the invention. Adhesive bonding or welding may be employed alone or in addition to the positive connection of the disk parts. For example, the number of pins necessary for pressing together can be kept low by means of points of adhesion. The disk parts can thereby also be manufactured as identical components. The welding method used could be, for example, reflector welding. However, the impeller requires only particularly little reworking if the welding method used is ultrasonic welding.
A contribution to further simplifying the assembly of the impeller according to the invention is made if one of the disk parts has catch recesses and if the other disk part has catch hooks penetrating into the catch recesses.
According to another advantageous development of the invention, the disk parts are reliably prestressed relative to one another if the disk parts have a bayonet fastening for connecting them.
The invention permits numerous embodiments. In order to make its basic principle even clearer, several of these are illustrated in the drawings and are described below.
In the drawings: